[mirror_ubuntu-bionic-kernel.git] / arch / x86 / include / asm / mmu_context.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_MMU_CONTEXT_H
#define _ASM_X86_MMU_CONTEXT_H

#include <asm/desc.h>
#include <linux/atomic.h>
#include <linux/mm_types.h>
#include <linux/pkeys.h>

#include <trace/events/tlb.h>

#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>

extern atomic64_t last_mm_ctx_id;

#ifndef CONFIG_PARAVIRT
static inline void paravirt_activate_mm(struct mm_struct *prev,
					struct mm_struct *next)
{
}
#endif	/* !CONFIG_PARAVIRT */

#ifdef CONFIG_PERF_EVENTS
extern struct static_key rdpmc_always_available;

static inline void load_mm_cr4(struct mm_struct *mm)
{
	if (static_key_false(&rdpmc_always_available) ||
	    atomic_read(&mm->context.perf_rdpmc_allowed))
		cr4_set_bits(X86_CR4_PCE);
	else
		cr4_clear_bits(X86_CR4_PCE);
}
#else
static inline void load_mm_cr4(struct mm_struct *mm) {}
#endif

#ifdef CONFIG_MODIFY_LDT_SYSCALL
/*
 * ldt_structs can be allocated, used, and freed, but they are never
 * modified while live.
 */
struct ldt_struct {
	/*
	 * Xen requires page-aligned LDTs with special permissions.  This is
	 * needed to prevent us from installing evil descriptors such as
	 * call gates.  On native, we could merge the ldt_struct and LDT
	 * allocations, but it's not worth trying to optimize.
	 */
	struct desc_struct	*entries;
	unsigned int		nr_entries;

	/*
	 * If PTI is in use, then the entries array is not mapped while we're
	 * in user mode.  The whole array will be aliased at the addressed
	 * given by ldt_slot_va(slot).  We use two slots so that we can allocate
	 * and map, and enable a new LDT without invalidating the mapping
	 * of an older, still-in-use LDT.
	 *
	 * slot will be -1 if this LDT doesn't have an alias mapping.
	 */
	int			slot;
};

/* This is a multiple of PAGE_SIZE. */
#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)

static inline void *ldt_slot_va(int slot)
{
	return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot);
}

/*
 * Used for LDT copy/destruction.
 */
static inline void init_new_context_ldt(struct mm_struct *mm)
{
	mm->context.ldt = NULL;
	init_rwsem(&mm->context.ldt_usr_sem);
}
int ldt_dup_context(struct mm_struct *oldmm, struct mm_struct *mm);
void destroy_context_ldt(struct mm_struct *mm);
void ldt_arch_exit_mmap(struct mm_struct *mm);
#else	/* CONFIG_MODIFY_LDT_SYSCALL */
static inline void init_new_context_ldt(struct mm_struct *mm) { }
static inline int ldt_dup_context(struct mm_struct *oldmm,
				  struct mm_struct *mm)
{
	return 0;
}
static inline void destroy_context_ldt(struct mm_struct *mm) { }
static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
#endif

static inline void load_mm_ldt(struct mm_struct *mm)
{
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	struct ldt_struct *ldt;

	/* READ_ONCE synchronizes with smp_store_release */
	ldt = READ_ONCE(mm->context.ldt);

	/*
	 * Any change to mm->context.ldt is followed by an IPI to all
	 * CPUs with the mm active.  The LDT will not be freed until
	 * after the IPI is handled by all such CPUs.  This means that,
	 * if the ldt_struct changes before we return, the values we see
	 * will be safe, and the new values will be loaded before we run
	 * any user code.
	 *
	 * NB: don't try to convert this to use RCU without extreme care.
	 * We would still need IRQs off, because we don't want to change
	 * the local LDT after an IPI loaded a newer value than the one
	 * that we can see.
	 */

	if (unlikely(ldt)) {
		if (static_cpu_has(X86_FEATURE_PTI)) {
			if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
				/*
				 * Whoops -- either the new LDT isn't mapped
				 * (if slot == -1) or is mapped into a bogus
				 * slot (if slot > 1).
				 */
				clear_LDT();
				return;
			}

			/*
			 * If page table isolation is enabled, ldt->entries
			 * will not be mapped in the userspace pagetables.
			 * Tell the CPU to access the LDT through the alias
			 * at ldt_slot_va(ldt->slot).
			 */
			set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
		} else {
			set_ldt(ldt->entries, ldt->nr_entries);
		}
	} else {
		clear_LDT();
	}
#else
	clear_LDT();
#endif
}

static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
{
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	/*
	 * Load the LDT if either the old or new mm had an LDT.
	 *
	 * An mm will never go from having an LDT to not having an LDT.  Two
	 * mms never share an LDT, so we don't gain anything by checking to
	 * see whether the LDT changed.  There's also no guarantee that
	 * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
	 * then prev->context.ldt will also be non-NULL.
	 *
	 * If we really cared, we could optimize the case where prev == next
	 * and we're exiting lazy mode.  Most of the time, if this happens,
	 * we don't actually need to reload LDTR, but modify_ldt() is mostly
	 * used by legacy code and emulators where we don't need this level of
	 * performance.
	 *
	 * This uses | instead of || because it generates better code.
	 */
	if (unlikely((unsigned long)prev->context.ldt |
		     (unsigned long)next->context.ldt))
		load_mm_ldt(next);
#endif

	DEBUG_LOCKS_WARN_ON(preemptible());
}

void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);

static inline int init_new_context(struct task_struct *tsk,
				   struct mm_struct *mm)
{
	mutex_init(&mm->context.lock);

	mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
	atomic64_set(&mm->context.tlb_gen, 0);

#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
		/* pkey 0 is the default and allocated implicitly */
		mm->context.pkey_allocation_map = 0x1;
		/* -1 means unallocated or invalid */
		mm->context.execute_only_pkey = -1;
	}
#endif
	init_new_context_ldt(mm);
	return 0;
}
static inline void destroy_context(struct mm_struct *mm)
{
	destroy_context_ldt(mm);
}

extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
		      struct task_struct *tsk);

extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
			       struct task_struct *tsk);
#define switch_mm_irqs_off switch_mm_irqs_off

#define activate_mm(prev, next)			\
do {						\
	paravirt_activate_mm((prev), (next));	\
	switch_mm((prev), (next), NULL);	\
} while (0);

#ifdef CONFIG_X86_32
#define deactivate_mm(tsk, mm)			\
do {						\
	lazy_load_gs(0);			\
} while (0)
#else
#define deactivate_mm(tsk, mm)			\
do {						\
	load_gs_index(0);			\
	loadsegment(fs, 0);			\
} while (0)
#endif

static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
{
	paravirt_arch_dup_mmap(oldmm, mm);
	return ldt_dup_context(oldmm, mm);
}

static inline void arch_exit_mmap(struct mm_struct *mm)
{
	paravirt_arch_exit_mmap(mm);
	ldt_arch_exit_mmap(mm);
}

#ifdef CONFIG_X86_64
static inline bool is_64bit_mm(struct mm_struct *mm)
{
	return	!IS_ENABLED(CONFIG_IA32_EMULATION) ||
		!(mm->context.ia32_compat == TIF_IA32);
}
#else
static inline bool is_64bit_mm(struct mm_struct *mm)
{
	return false;
}
#endif

static inline void arch_bprm_mm_init(struct mm_struct *mm,
		struct vm_area_struct *vma)
{
	mpx_mm_init(mm);
}

static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
			      unsigned long start, unsigned long end)
{
	/*
	 * mpx_notify_unmap() goes and reads a rarely-hot
	 * cacheline in the mm_struct.  That can be expensive
	 * enough to be seen in profiles.
	 *
	 * The mpx_notify_unmap() call and its contents have been
	 * observed to affect munmap() performance on hardware
	 * where MPX is not present.
	 *
	 * The unlikely() optimizes for the fast case: no MPX
	 * in the CPU, or no MPX use in the process.  Even if
	 * we get this wrong (in the unlikely event that MPX
	 * is widely enabled on some system) the overhead of
	 * MPX itself (reading bounds tables) is expected to
	 * overwhelm the overhead of getting this unlikely()
	 * consistently wrong.
	 */
	if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
		mpx_notify_unmap(mm, vma, start, end);
}

#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
static inline int vma_pkey(struct vm_area_struct *vma)
{
	unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
				      VM_PKEY_BIT2 | VM_PKEY_BIT3;

	return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
}
#else
static inline int vma_pkey(struct vm_area_struct *vma)
{
	return 0;
}
#endif

/*
 * We only want to enforce protection keys on the current process
 * because we effectively have no access to PKRU for other
 * processes or any way to tell *which * PKRU in a threaded
 * process we could use.
 *
 * So do not enforce things if the VMA is not from the current
 * mm, or if we are in a kernel thread.
 */
static inline bool vma_is_foreign(struct vm_area_struct *vma)
{
	if (!current->mm)
		return true;
	/*
	 * Should PKRU be enforced on the access to this VMA?  If
	 * the VMA is from another process, then PKRU has no
	 * relevance and should not be enforced.
	 */
	if (current->mm != vma->vm_mm)
		return true;

	return false;
}

static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
		bool write, bool execute, bool foreign)
{
	/* pkeys never affect instruction fetches */
	if (execute)
		return true;
	/* allow access if the VMA is not one from this process */
	if (foreign || vma_is_foreign(vma))
		return true;
	return __pkru_allows_pkey(vma_pkey(vma), write);
}

/*
 * This can be used from process context to figure out what the value of
 * CR3 is without needing to do a (slow) __read_cr3().
 *
 * It's intended to be used for code like KVM that sneakily changes CR3
 * and needs to restore it.  It needs to be used very carefully.
 */
static inline unsigned long __get_current_cr3_fast(void)
{
	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
		this_cpu_read(cpu_tlbstate.loaded_mm_asid));

	/* For now, be very restrictive about when this can be called. */
	VM_WARN_ON(in_nmi() || preemptible());

	VM_BUG_ON(cr3 != __read_cr3());
	return cr3;
}

#endif /* _ASM_X86_MMU_CONTEXT_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1965aae3 PA	2	#ifndef _ASM_X86_MMU_CONTEXT_H
1965aae3 PA	3	#define _ASM_X86_MMU_CONTEXT_H
c3c2fee3 JF	4
c3c2fee3 JF	5	#include <asm/desc.h>
60063497	6	#include <linux/atomic.h>
d17d8f9d	7	#include <linux/mm_types.h>
7d06d9c9	8	#include <linux/pkeys.h>
d17d8f9d DH	9
	10	#include <trace/events/tlb.h>
	11
c3c2fee3 JF	12	#include <asm/pgalloc.h>
	13	#include <asm/tlbflush.h>
	14	#include <asm/paravirt.h>
fe3d197f	15	#include <asm/mpx.h>
f39681ed AL	16
	17	extern atomic64_t last_mm_ctx_id;
	18
c3c2fee3	19	#ifndef CONFIG_PARAVIRT
c3c2fee3 JF	20	static inline void paravirt_activate_mm(struct mm_struct *prev,
	21	struct mm_struct *next)
	22	{
	23	}
	24	#endif /* !CONFIG_PARAVIRT */
	25
7911d3f7	26	#ifdef CONFIG_PERF_EVENTS
a6673429 AL	27	extern struct static_key rdpmc_always_available;
a6673429 AL	28
7911d3f7 AL	29	static inline void load_mm_cr4(struct mm_struct *mm)
7911d3f7 AL	30	{
a833581e	31	if (static_key_false(&rdpmc_always_available) \|\|
a6673429	32	atomic_read(&mm->context.perf_rdpmc_allowed))
7911d3f7 AL	33	cr4_set_bits(X86_CR4_PCE);
	34	else
	35	cr4_clear_bits(X86_CR4_PCE);
	36	}
	37	#else
	38	static inline void load_mm_cr4(struct mm_struct *mm) {}
	39	#endif
	40
a5b9e5a2	41	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	42	/*
	43	* ldt_structs can be allocated, used, and freed, but they are never
	44	* modified while live.
	45	*/
	46	struct ldt_struct {
	47	/*
	48	* Xen requires page-aligned LDTs with special permissions. This is
	49	* needed to prevent us from installing evil descriptors such as
	50	* call gates. On native, we could merge the ldt_struct and LDT
	51	* allocations, but it's not worth trying to optimize.
	52	*/
f55f0501 AL	53	struct desc_struct *entries;
	54	unsigned int nr_entries;
	55
	56	/*
	57	* If PTI is in use, then the entries array is not mapped while we're
	58	* in user mode. The whole array will be aliased at the addressed
	59	* given by ldt_slot_va(slot). We use two slots so that we can allocate
	60	* and map, and enable a new LDT without invalidating the mapping
	61	* of an older, still-in-use LDT.
	62	*
	63	* slot will be -1 if this LDT doesn't have an alias mapping.
	64	*/
	65	int slot;
37868fe1 AL	66	};
37868fe1 AL	67
f55f0501 AL	68	/* This is a multiple of PAGE_SIZE. */
	69	#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)
	70
	71	static inline void *ldt_slot_va(int slot)
	72	{
f55f0501	73	return (void )(LDT_BASE_ADDR + LDT_SLOT_STRIDE slot);
f55f0501 AL	74	}
f55f0501 AL	75
a5b9e5a2 AL	76	/*
	77	* Used for LDT copy/destruction.
	78	*/
a4828f81 TG	79	static inline void init_new_context_ldt(struct mm_struct *mm)
	80	{
	81	mm->context.ldt = NULL;
	82	init_rwsem(&mm->context.ldt_usr_sem);
	83	}
	84	int ldt_dup_context(struct mm_struct oldmm, struct mm_struct mm);
39a0526f	85	void destroy_context_ldt(struct mm_struct *mm);
f55f0501	86	void ldt_arch_exit_mmap(struct mm_struct *mm);
a5b9e5a2	87	#else /* CONFIG_MODIFY_LDT_SYSCALL */
a4828f81 TG	88	static inline void init_new_context_ldt(struct mm_struct *mm) { }
	89	static inline int ldt_dup_context(struct mm_struct *oldmm,
	90	struct mm_struct *mm)
a5b9e5a2 AL	91	{
	92	return 0;
	93	}
f55f0501 AL	94	static inline void destroy_context_ldt(struct mm_struct *mm) { }
f55f0501 AL	95	static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
a5b9e5a2 AL	96	#endif
a5b9e5a2 AL	97
37868fe1 AL	98	static inline void load_mm_ldt(struct mm_struct *mm)
37868fe1 AL	99	{
a5b9e5a2	100	#ifdef CONFIG_MODIFY_LDT_SYSCALL
37868fe1 AL	101	struct ldt_struct *ldt;
37868fe1 AL	102
3382290e WD	103	/* READ_ONCE synchronizes with smp_store_release */
3382290e WD	104	ldt = READ_ONCE(mm->context.ldt);
37868fe1 AL	105
	106	/*
	107	* Any change to mm->context.ldt is followed by an IPI to all
	108	* CPUs with the mm active. The LDT will not be freed until
	109	* after the IPI is handled by all such CPUs. This means that,
	110	* if the ldt_struct changes before we return, the values we see
	111	* will be safe, and the new values will be loaded before we run
	112	* any user code.
	113	*
	114	* NB: don't try to convert this to use RCU without extreme care.
	115	* We would still need IRQs off, because we don't want to change
	116	* the local LDT after an IPI loaded a newer value than the one
	117	* that we can see.
	118	*/
	119
f55f0501 AL	120	if (unlikely(ldt)) {
	121	if (static_cpu_has(X86_FEATURE_PTI)) {
	122	if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
	123	/*
	124	* Whoops -- either the new LDT isn't mapped
	125	* (if slot == -1) or is mapped into a bogus
	126	* slot (if slot > 1).
	127	*/
	128	clear_LDT();
	129	return;
	130	}
	131
	132	/*
	133	* If page table isolation is enabled, ldt->entries
	134	* will not be mapped in the userspace pagetables.
	135	* Tell the CPU to access the LDT through the alias
	136	* at ldt_slot_va(ldt->slot).
	137	*/
	138	set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
	139	} else {
	140	set_ldt(ldt->entries, ldt->nr_entries);
	141	}
	142	} else {
37868fe1	143	clear_LDT();
f55f0501	144	}
a5b9e5a2 AL	145	#else
	146	clear_LDT();
	147	#endif
73534258 AL	148	}
	149
	150	static inline void switch_ldt(struct mm_struct prev, struct mm_struct next)
	151	{
	152	#ifdef CONFIG_MODIFY_LDT_SYSCALL
	153	/*
	154	* Load the LDT if either the old or new mm had an LDT.
	155	*
	156	* An mm will never go from having an LDT to not having an LDT. Two
	157	* mms never share an LDT, so we don't gain anything by checking to
	158	* see whether the LDT changed. There's also no guarantee that
	159	* prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
	160	* then prev->context.ldt will also be non-NULL.
	161	*
	162	* If we really cared, we could optimize the case where prev == next
	163	* and we're exiting lazy mode. Most of the time, if this happens,
	164	* we don't actually need to reload LDTR, but modify_ldt() is mostly
	165	* used by legacy code and emulators where we don't need this level of
	166	* performance.
	167	*
	168	* This uses \| instead of \|\| because it generates better code.
	169	*/
	170	if (unlikely((unsigned long)prev->context.ldt \|
	171	(unsigned long)next->context.ldt))
	172	load_mm_ldt(next);
	173	#endif
37868fe1 AL	174
	175	DEBUG_LOCKS_WARN_ON(preemptible());
	176	}
	177
b956575b	178	void enter_lazy_tlb(struct mm_struct mm, struct task_struct tsk);
6826c8ff	179
39a0526f DH	180	static inline int init_new_context(struct task_struct *tsk,
	181	struct mm_struct *mm)
	182	{
c2b3496b PZ	183	mutex_init(&mm->context.lock);
c2b3496b PZ	184
f39681ed AL	185	mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
	186	atomic64_set(&mm->context.tlb_gen, 0);
	187
a4828f81	188	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
e8c24d3a	189	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
8fc96d16	190	/* pkey 0 is the default and allocated implicitly */
e8c24d3a DH	191	mm->context.pkey_allocation_map = 0x1;
	192	/* -1 means unallocated or invalid */
	193	mm->context.execute_only_pkey = -1;
	194	}
a4828f81 TG	195	#endif
	196	init_new_context_ldt(mm);
	197	return 0;
39a0526f DH	198	}
	199	static inline void destroy_context(struct mm_struct *mm)
	200	{
	201	destroy_context_ldt(mm);
	202	}
	203
69c0319a AL	204	extern void switch_mm(struct mm_struct prev, struct mm_struct next,
69c0319a AL	205	struct task_struct *tsk);
6826c8ff	206
078194f8 AL	207	extern void switch_mm_irqs_off(struct mm_struct prev, struct mm_struct next,
	208	struct task_struct *tsk);
	209	#define switch_mm_irqs_off switch_mm_irqs_off
c3c2fee3 JF	210
	211	#define activate_mm(prev, next) \
	212	do { \
	213	paravirt_activate_mm((prev), (next)); \
	214	switch_mm((prev), (next), NULL); \
	215	} while (0);
	216
6826c8ff BG	217	#ifdef CONFIG_X86_32
	218	#define deactivate_mm(tsk, mm) \
	219	do { \
ccbeed3a	220	lazy_load_gs(0); \
6826c8ff BG	221	} while (0)
	222	#else
	223	#define deactivate_mm(tsk, mm) \
	224	do { \
	225	load_gs_index(0); \
	226	loadsegment(fs, 0); \
	227	} while (0)
	228	#endif
c3c2fee3	229
c10e83f5	230	static inline int arch_dup_mmap(struct mm_struct oldmm, struct mm_struct mm)
a1ea1c03 DH	231	{
a1ea1c03 DH	232	paravirt_arch_dup_mmap(oldmm, mm);
a4828f81	233	return ldt_dup_context(oldmm, mm);
a1ea1c03 DH	234	}
	235
	236	static inline void arch_exit_mmap(struct mm_struct *mm)
	237	{
	238	paravirt_arch_exit_mmap(mm);
f55f0501	239	ldt_arch_exit_mmap(mm);
a1ea1c03 DH	240	}
a1ea1c03 DH	241
b0e9b09b DH	242	#ifdef CONFIG_X86_64
	243	static inline bool is_64bit_mm(struct mm_struct *mm)
	244	{
97f2645f	245	return !IS_ENABLED(CONFIG_IA32_EMULATION) \|\|
b0e9b09b DH	246	!(mm->context.ia32_compat == TIF_IA32);
	247	}
	248	#else
	249	static inline bool is_64bit_mm(struct mm_struct *mm)
	250	{
	251	return false;
	252	}
	253	#endif
	254
fe3d197f DH	255	static inline void arch_bprm_mm_init(struct mm_struct *mm,
	256	struct vm_area_struct *vma)
	257	{
	258	mpx_mm_init(mm);
	259	}
	260
1de4fa14 DH	261	static inline void arch_unmap(struct mm_struct mm, struct vm_area_struct vma,
	262	unsigned long start, unsigned long end)
	263	{
c922228e DH	264	/*
	265	* mpx_notify_unmap() goes and reads a rarely-hot
	266	* cacheline in the mm_struct. That can be expensive
	267	* enough to be seen in profiles.
	268	*
	269	* The mpx_notify_unmap() call and its contents have been
	270	* observed to affect munmap() performance on hardware
	271	* where MPX is not present.
	272	*
	273	* The unlikely() optimizes for the fast case: no MPX
	274	* in the CPU, or no MPX use in the process. Even if
	275	* we get this wrong (in the unlikely event that MPX
	276	* is widely enabled on some system) the overhead of
	277	* MPX itself (reading bounds tables) is expected to
	278	* overwhelm the overhead of getting this unlikely()
	279	* consistently wrong.
	280	*/
	281	if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
	282	mpx_notify_unmap(mm, vma, start, end);
1de4fa14 DH	283	}
1de4fa14 DH	284
7d06d9c9	285	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
8f62c883 DH	286	static inline int vma_pkey(struct vm_area_struct *vma)
8f62c883 DH	287	{
8f62c883 DH	288	unsigned long vma_pkey_mask = VM_PKEY_BIT0 \| VM_PKEY_BIT1 \|
8f62c883 DH	289	VM_PKEY_BIT2 \| VM_PKEY_BIT3;
7d06d9c9 DH	290
	291	return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
	292	}
	293	#else
	294	static inline int vma_pkey(struct vm_area_struct *vma)
	295	{
	296	return 0;
8f62c883	297	}
7d06d9c9	298	#endif
8f62c883	299
33a709b2 DH	300	/*
	301	* We only want to enforce protection keys on the current process
	302	* because we effectively have no access to PKRU for other
	303	* processes or any way to tell which PKRU in a threaded
	304	* process we could use.
	305	*
	306	* So do not enforce things if the VMA is not from the current
	307	* mm, or if we are in a kernel thread.
	308	*/
	309	static inline bool vma_is_foreign(struct vm_area_struct *vma)
	310	{
	311	if (!current->mm)
	312	return true;
	313	/*
	314	* Should PKRU be enforced on the access to this VMA? If
	315	* the VMA is from another process, then PKRU has no
	316	* relevance and should not be enforced.
	317	*/
	318	if (current->mm != vma->vm_mm)
	319	return true;
	320
	321	return false;
	322	}
	323
1b2ee126	324	static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
d61172b4	325	bool write, bool execute, bool foreign)
33a709b2	326	{
d61172b4 DH	327	/* pkeys never affect instruction fetches */
	328	if (execute)
	329	return true;
33a709b2	330	/* allow access if the VMA is not one from this process */
1b2ee126	331	if (foreign \|\| vma_is_foreign(vma))
33a709b2 DH	332	return true;
	333	return __pkru_allows_pkey(vma_pkey(vma), write);
	334	}
	335
d6e41f11 AL	336	/*
d6e41f11 AL	337	* This can be used from process context to figure out what the value of
6c690ee1	338	* CR3 is without needing to do a (slow) __read_cr3().
d6e41f11 AL	339	*
	340	* It's intended to be used for code like KVM that sneakily changes CR3
	341	* and needs to restore it. It needs to be used very carefully.
	342	*/
	343	static inline unsigned long __get_current_cr3_fast(void)
	344	{
50fb83a6	345	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
47061a24	346	this_cpu_read(cpu_tlbstate.loaded_mm_asid));
10af6235	347
d6e41f11	348	/* For now, be very restrictive about when this can be called. */
4c07f904	349	VM_WARN_ON(in_nmi() \|\| preemptible());
d6e41f11	350
6c690ee1	351	VM_BUG_ON(cr3 != __read_cr3());
d6e41f11 AL	352	return cr3;
	353	}
	354
1965aae3	355	#endif /* _ASM_X86_MMU_CONTEXT_H */